1. Field of the Invention
The present invention relates to a circuit board for mounting a multilayer chip capacitor and a circuit board apparatus including the multilayer chip capacitor, and more particularly, to a circuit board for mounting a vertical multilayer chip capacitor, the circuit board having a capacitor-mounting structure useful for high frequency decoupling, and a circuit board apparatus including the circuit board and the vertical multilayer chip capacitor.
2. Description of the Related Art
A multilayer chip capacitor is used as a decoupling capacitor arranged in a high frequency circuit such as a power supply circuit of CPU or other LSI. To stabilize a power supply circuit, the multilayer chip capacitor is required to have a low equivalent series inductance (ESL). This requirement is further increased as electronic devices tend to be operated at high frequency and high current. A multilayer chip capacitor is also used as an electromagnetic interference (EMI) filter. In this case, a low ESL is preferable for a high frequency noise removal effect and a good attenuation property.
A decoupling capacitor can be electrically connected to a mounting pad on a package circuit board by soldering. The mounting pad may be connected to another external circuit through conductive patterns or conductive vias in the board. Depending on a mounting structure of a capacitor, a loop inductance including the capacitor may become different. Such a difference in loop inductance has an effect on an impedance of an entire power distribution network. To design a stable power distribution network, the loop inductance may be reduced as possible.
To reduce ESL, U.S. Pat. No. 5,880,925 discloses a multilayer capacitor in which leads of first and second internal electrodes having opposite polarities, are disposed in an interdigitated arrangement. However, in order to implement more stable power distribution network or remove high frequency noise more effectively, it is necessary to further reduce ESL of a capacitor and/or a loop inductance caused by pads, wiring, vias or other conductive patterns.